The present invention relates to a method for protecting and marking products by using microparticles, which are to be attached or added to the product, each microparticle having several color layers forming a code, wherein for each individual product two or more differently coded microparticle groups are used, with the first microparticle group containing in its code the same information for a plurality of products, and with the second or subsequent microparticle group containing in its code an information which is individual for each individual product or for few products. Furthermore, the invention relates to a variation of the method to form a pure numbering method.
A method of the kind mentioned first is known from U.S. Pat. No. 4,390,452. It is described in this document that a substance or an object, which generally means a product, can be provided with two or more: differently coded microparticle groups, e.g., a first microparticle group describing the manufacturer, and a second microparticle group describing individual production units. As a first example, automobile varnish is cited which may be characterized by a first microparticle group describing the varnish plant, and with a second microparticle group describing the day or the week of the varnish production. As a second example, animals are cited which may be marked regarding the owner with one group, and regarding a biological treatment with the other group, wherein the markings may also be applied at different points in time. As it is particularly obvious from the example of the automobile varnish, the number of the production units to be differentiated is relatively small, in this case, e.g., 365 for the number of the days or 53 for the number of the weeks of one year. On the other hand, for each day to be marked or for each week to be marked, an individual microparticle code has to be used. Thus, the number of the differently coded microparticles corresponds directly to the number of the days to be marked or weeks to be marked or to other units to be marked. Such a method is tolerable with relatively small numbers, however, when the numbers reach a higher order, such a method is absolutely inefficient. This inefficiency is in particular caused by the fact that often very great numbers of products are produced in a product series, and that if for each product an own individual marking is required, for each of these markings only a very small amount of microparticles is required. The production of a very great number of differently coded microparticles in very small amounts of each code is very costly for the producer of microparticles, and not economical. For the user of the microparticles such a method requires a very high effort in logistics for storing, for associating and for attaching or adding of the correct microparticles to each associated piece of product.
It is an object of the present invention to provide a method of the kind mentioned above which avoids the drawbacks mentioned, and which is able to protect and mark individual products, even in case of great product numbers, with a reasonable economical and logistic effort. Furthermore, the method shall be able to be varied such that it can be used for a pure numbering of products whenever an overall marking, e.g., with a manufacturing code, is not required or desired.
For attaining the first part of the object a method of the kind mentioned before is proposed which is characterized in that the second microparticle group is formed by microparticles describing the unit place and the tens place of a decimal number, that an optionally provided third microparticle group is formed by microparticles describing the hundreds place and the thousands place of a decimal number, that an optionally provided fourth microparticle group is formed by microparticles describing the ten thousands place and the hundred thousands place of a decimal number, and that the microparticles of each microparticle group have at least one own group marking color layer.